Integrated circuit die may need to be heated for multiple purposes. The die may be heated in order to determine performance at the operating temperature range specified for that die, to perform accelerated life testing by heating the die beyond the specified temperature range to induce accelerated aging, or to heat the die to a preset temperature in order to eliminate those die that may experience early failure.
Integrated circuits may need to be designed to function at different operating temperature ranges based on their intended use. These circuits may be tested at the maximum temperature of the operating temperature range in order to ensure that each individual die can perform at that temperature. Typically, industrial electronics may require that the integrated circuits operate at 85° C., and other high-temperature applications, such as some military electronics, may require the integrated circuits to operate at a temperature of 125° C. or higher.
The die of integrated circuits may fail over time due to stresses from temperature variations. The die may be heated to a temperature beyond the specified operating range in order to perform accelerated life testing, i.e., to heat the die to various temperatures in order to approximate the die's ability to withstand environmental stresses.
The integrated circuits may also be tested to verify the connections between the die contacts and the package contacts. During the life cycle of the die, the connections between the die and the package may fail. Thus, by performing accelerated life testing on a packaged die, failures in the connections between the die and the package may be detected.
Typically, die are heated in an oven to bring the die to the desired heat testing temperature. The die may be batch-heated in a package, and may all be heated to the same temperature in the oven. The die may be tested to determine performance at elevated temperatures. Heating the die in an oven may require that testing components such as connectors, printed wiring boards, sockets, resistors, capacitors, and driver chips be located inside the oven enclosure, and thus the testing components may undergo significant stress due to prolonged exposure to elevated temperatures.
A multi-chip module (“MCM) may comprise several die in a single package. The MCM may fail if a single die fails. Thus, it may be undesirable to heat-test the die after incorporating multiple die into a single package, as all the die in the MCM may be discarded if a single die fails.
Therefore, an improved method of heat testing integrated circuit die is needed.